/Engine/Source/Runtime/RHICore/Public/RHICoreTransientResourceAllocator.h
The RHI transient heap system is a base class for the platform implementation. It has a persistent lifetime and contains a cache of transient heaps. The transient allocator acquires heaps from the system and forfeits them at the end of its lifetime. Garbage collection of heaps is done using an internal counter that increments with each GarbageCollect call. This should be done periodically. Heaps older than a platform-specified fence latency are destroyed. Additionally, statistics are gathered automatically and reported to the 'rhitransientmemory' stats group.
class FRHITransientHeapCache : public [IRHITransientMemoryCache](API\Runtime\RHICore\IRHITransientMemoryCache)